Patients with neuroblastoma, or other GD2-positive malignancies are being treated with a combination of ch14.18 and GM-CSF following autologous bone marrow transplant in order to improve relapse-free survival rates and overall survival rates. This phase I study aims to determine the maximum tolerable dose of chimeric human/murine monoclonal antibody ch14.18 given in combination with standard dose GM-CSF, to determine the toxicities of ch14.18 given on this schedule to pediatric patients, and the PK behavior of ch14.18.